Rocker arm



E. K. RALSTON Feb. 3, 1959 ROCKER ARM Filed April 15 1953 3 Sheets-Sheet1 Feb. 3, 1959 E. K. RALSTON 71,

ROCKER ARM Filed April 13, 1953 v I s Sheets-Sheet 2 m? v, 2 u

' 5 H012 I Fa/szozz Feb. 3; 1959 E. RALSTON 2,871,720

I ROCKER ARM Filed April 13, 1953 I 5 Sheets-Sheet s United StatesPatent ROCKER ARM Eldon K. Ralston, Lyndhurst, Ohio, assignor toThompiplilr Products, Inc., Cleveland, Ohio, a corporation of Thisinvention relates to rocker arms for internal combustion engines and thelike having maximum rigidity and strength together with minimum weightand polar moment of inertia. Specifically, this invention relates torocker arms which are economical to manufacture and provide trussesbetween the push rod or tappet and the valve actuated thereby.

In accordance with this invention top and bottom metal straps disposedflatwise receive a tubular metal bushing therebetween and provide trussmembers substantially free from beam action to transmit loads whilerocking about a shaft support for the bushing. A bearing sleeve liner isprovided in the bushing. The bushing itself acts as a strut transferringload between the top and bottom straps and compares with a web member ina bridge suspension.

- The straps converge at a point as close as possible to the center lineof load application at each end of the rocker arm for eliminating beamaction between the load pointand the contactpoint. The lower strap wrapsand supports the bushing over an area that carries substantially theentire bearing load. The valve contacting end of the straps is moredistantly spaced from the bush-- ing than the push rod or tappetcontacting end of the straps and a spacer is provided between the strapsat tralizes the tendency of a beam deflection by acting as the push rodengaging end thereof. This spacer neua link forming the side of aquadralateral. Since the bending moment is negligible at the valvecontacting end of the rocker arm the spacer or link is not necessary atthe valve end. The straps converge rather abruptly from the bushing tothe push rod contacting end and converge along a gentle slope from thebushing to the valve contacting end. This provides two triangulartrusses forming'rigid frames no member of which can be deformed withoutdeforming the other member. Beam bending action is thereby minimized.

It is then an object of this invention to provide a truss type rockerarm for internal combustion engines.

Another object of this invention is to provide a low inertia, lightweight, strong and rigid rocker arm.

A further object of this invention is to provide rocker arms havingflatwise disposed top and bottom straps embracing a tubular rock shaftreceiving bushing and converging from both sides of the bushing toprovide a short push rod contact end portion and a long valve contactend portion.

A further object of the invention is to provide a rocker arm composed offlatwise disposed top and bottom steel strips over the top and bottom ofa tubular bushing and converging from the bushing to connected ends forcoaction with a push rod and a valve tip respectively.

A specific object of the invention is to provide a fabricated truss typelight weight and economical rocker arm with struts of uniform thicknessbut varying in width to uniformly distribute stresses encounteredtherein.

A further object of this invention is to provide a rocker arm composedof a bushing and strap members secured to the bushing and to each otherso as to form twotriangular trusses for transmitting loads between apush rod and a valve.

' straps and spacer 15.

' screw-and the top strap 11.

Patented Feb. 3, 1959 ice Other and further objects of this inventionwill be apparent to those skilled in the art from the following detaileddescription of the annexed sheets of drawings, which, by way ofpreferred examples, illustrate several embodiments of the invention.

On the drawings:

Figure 1 is a side elevational view, with a part in verticalcross-section, illustrating a rocker arm according to this inventionoperatively mounted on a rock shaft and transmitting forces between apush rod and a valve.

Figure 2 is a top plan view of the rocker arm of Figure 1 illustratingthe varying width of the truss struts.

Figure 3 is a longitudinal cross-sectional view along the line III-IIIof Figure 2.

Figure 3A is a fragmentary view similar to Figure 3 but showing anotherform of spacer.

Figure 4 is a side elevational view of a modified form of rocker armaccording to this invention.

Figure 5 is a longitudinal cross-sectional view ofthe rocker arm ofFigure 4.

Figure 6 is aside elevational view of still another modified form ofrocker arm according to this invention.

Figure 7 is a longitudinal cross-sectional view of a further modifiedform of rocker arm according to this invention.

Figure 8 is a transverse cross-sectional view, with parts in elevation,taken along the line VIII-VIII of Figure 7. w

Figure 9 is a fragmentary longitudinal cross-sectional view of stillanothermodified rocker arm according to this invention.

Figure 10 is a transverse cross-sectional view, with parts in elevation,taken along the line X--X of Figure 9.

Figure 11 is a fragmentary side elevational view of a portion of amodified rocker arm according to this invention carrying a roller forengaging the'tip end of a valve.

Figure 12 is an isometric view of the roller assembly of Figure 11.

Figure 13 is a fragmentary v1ew illustrating the man-- ner in which thestrap members of the rocker arm are centered on the bushing.

Figure 14 is a side elevational view of a rockerarm according to thisinvention illustrating the manner in which forces are applied thereto inoperation.

Figure 15 is a force diagram illustrating the force vectors applied tothe rocker arm at the triangular truss formed on the push rod endportion of the arm.

Figure 16 is a view similar to Figure 15 but illustrating the forcevectors at the valve tip end portionof the ing the manner in which thelinkage controls deflection.-

As shown on the drawings:

The rocker arm 10 of'Figures 1'to'3 includes a top strap 11, a bottomstrap 12, a tube 13, a bearing liner 14 in the tube 13, a spacer 15between the straps 11 and 12 at the push rod contact end of the rockerarm, and an internally threaded eylet 16 inserted through the Thiseyelet 16, as shown in Figure 1, receives an adjustment screw 17therethrough. The adjustment screw has a rounded end 17a fitting in therecessed top end of a push rod 18. A locknut 19 on the adjusting screwis provided between the head 17b of the The top strap 11 issubstantially straight being bowed at 11a to fit around a small arc ofthe top of the tube 13. I

This bowed portion 11a is bonded to the top of the tube by any suitablebrazed bonds or welds 20. The strap slopes downwardly from the bend 11ato provide a long legllb and a short leg 110. The long leg 11bterminates in a substantially horizontal rounded end portion 11d whiletheshort leg 11c terminates in a flat eye He receiving the threadedeyelet 16 therethrough. This eye He is affixed to the eyelet by weldedor brazed bonds2 1- and the eyelet also has an out-turned flange 16aspun over the top of the: eye 112.

The bottom strap 12 is bowed much more than the top strap 11 and has anarcuate portion 12a lapping about the lower third of the tube. 13 andbonded thereto by braze or weld. bonds 22. The strap 12 slopes upwardlyfrom the bowed portion 12:: to provide a relatively long leg 12b and avrelatively short leg 120. The long leg 12b terminates in a substantiallyhorizontal end 12d with a somewhat rounded bottom. contour. A weld orbraze bond 23 unites the end portions 11d and 12d of the straps 11 and12. The end of the short leg 12c terminates in an eye 12e similar to.the eye He and receiving the eyelet 16 therethrough. Braze or weld bonds24 unite the spacer 15 with the eye He and the eyelet 16 is spun overthe bottom of the eye 12:: to provide a flange 16b underlying theeye.

The straps 11 and 12 are of uniform thickness throughout their lengths.as shown in Figures 1 and 3.

The rounded end 12d of the strap 12 acts on the tip end of a valve stem25 to compress the valve spring 25a thereby to open the valve when thepush rod 18 raises the adjusting screw 17.

The tube 13 is most economically formed as a butted cylindrical stampingwith the butted front 13a thereof at the top under the bowed portion 11aof the top strap 11. When the straps are brazed on the tube this jointis also brazed closed. Alternately the tube 13 can be economicallyformed of butt welded tubing with the welded seam 13a at the top of therocker arm as shown. As will be hereinafter explained, the bearingforces on the tube 13 are applied to the bottom of the tube. As shown,the bearing liner 14 for the tube is rotatably mounted on alubricant-fed hollow rock shaft 26 having a hole 26a in the bottomthereof to lubricate the bearing liner 14.

As shown in Figure 2, both straps 11 and 12 have the same thickness buteach strap varies in width along its length and lies flatwise on thetube 13 which extends on both sides beyond the edges of the straps. Thewider portions of the straps are at the push rod end. This arrangementprovides a long legged triangular truss and a short legged triangulartruss with legs of uniform thickness but varying in width to uniformlydistribute stresses. The long legged truss is composed of the strap legs11b and 12b and one half of the tube 13. The short legged truss iscomposed of the strap portions 11c and 120 and the other half of thetube. These triangular assemblies act as true truss suspension membersin that no one member in the truss combination can be deformed withoutdeforming another member. The only possible beam supports of the entireassembly occur at the extreme ends of the trusses and, as will behereinafter explained, the spacer 15 together with the inserted eyelet16 serve to provide a linkage which minimizes beam bending.

If desired as shown in Figure 3A the spacer can take the form of acurved stamped piece 15' overlying the highly curved leg 120 of thestrap 12 and brazed thereto to increase the brazing contact area and toreinforce the leg 120.

In the modification a of Figures 4 and 5, parts identical with partsdescribed in Figures 1 to 3, have been marked with the same referencenumerals. In the modification 10a, the ends of the long legs 11b and 12bof the straps 11 and 12 are not bowed or curved. These ends portions 11dand 12d are flat and fully mate with each other. The weld bond 23 of theembodiment 19 is eliminated and instead of a round head rivet 27 has theshank 27a thereof snugly fitted in apertures of theflat ends 11d and12d. A spun over outturned flange 27b on the shank 27a overlies the end11d of the top strap 11 and a rounded head 27c underlies the portion 12dof the strap 12. The rounded head 27c acts on the tip end of the valvestem in the same manner as the rounded end 12d in the embodiment 10.However, the rivet head reinforces the long end of the assembly anddecreases the beam effect.

In the modification 10b of Figure 6, parts identical with partsdescribed in Figures 1 to 5 have been marked with the same referencenumerals. In Figure 6 the long legs 11]; and 12b of the straps 11 and 12have spaced apart fiat ends 11d" and 12d" with a spacer 28 therebetweenand welded thereto by weld bonds 29. The rounded head 270 of the rivet27 underlies the portion 12d" while the spun over flange 27b of therivet overlies the portion 11d". portions 11d and 124" in the samemanner as the spacer 15 between the eyes 11a and 122. This linkageeffect further decreases any beam action at the valve contact end of therocker arm.

In the embodiment shown in Figures 7 and 8, parts identical with partsdescribed in Figures 1 to 6 have been marked with the same referencenumerals. In the rocker arm lllc as shown in Figure 7, the end portions112 and 12e of the straps 1-1 and 12 receive the spacer 1S therebetweenand receive a plug 30 therethrough with spun over end flanges Slla and30b securing the plug in position. This plug has a fragmental sphericalrecess 31 in its bottom face receiving the ball end 32 of a push rod 33.A passageway 30c connects the recess 31 with a side wall of the plug.

The top strap 11 receives thereover a hollow ribbed strap 34 having acentral raised rib 34a providing a passageway 34b between the top faceof the strap 11 and the bottom face of the strap 34. This strap 34 has acontour following the contour of the strap 11 and has flat eye end 340overlying the eye end He and in turn, having flange 30a of the plug 30spun thereover.

A hole 35 is formed through the top of the tube 13 and liner 14 inalignment with a hole 36 formed through the strap 11. The registeringholes 35 and 36 feed lubricant supplied from the hollow rock shaft 26 tothe passageway 34- which in turn, feeds the passageway 300 in the plug30 to lubricate the socket 31 for the push rod.

The flat front ends 11d and 12d of the long legs 11b and 12b of thestraps receive a rivet 27 therethrough in the same manner as describedin connection with Figure 5 but this rivet 27 has a longer shank so thatit can project through the end 34d of the top strap 34 and have anouttnrned flange 27b spun over this top strap.

The rocker arm 100 thus has a covered lubricant passage for lubricatingthe push rod with lubricant supplied from the bearing or rock shaft.

In the modification 10d of Figures 9 and 10, parts identical with thosepreviously described have been marked with the same reference numerals.As shown, a top strap 11' has a central-corrugation therein providing anopen bottomed passage 37 in the short leg thereof communicating with thebore 30c of the plug 30 to supply lubricant to the recess 31 of theplug. The tube 13' has a raised rib 38 along the top portion thereofproviding a passageway receiving rock shaft supplied lubricant from thehole 35 in the liner 14 and discharging the lubricant through a hole 39into the open bottomed passage 37 from which it will flow to the bore300. In this embodiment, therefore, an open bottomed lubricant flowpassage is provided in the upper strap and is fed from a channelprovided in the tube.

In the embodiment 162 of Figure 11 the long legs 11b and 12b of thestraps 11 and 12 have their forward ends bowed as at 11d' and 1211" toprovide a roller recess in the bottom face of the assembly. A groove 44)is pro- The spacer 28 provides alinkage between the vided in the raisedend '11d' to receive a wire hanger 41 for a roller 42 which rides in therecess. As shown in Figure 12, this hanger 41 is a U-shaped member andhas the bight portion 41a thereof for fitting in the groove 40 togetherwith side legs 41b straddling the strap 11 and having rounded endportions 410 on the legs 41b merging with bottom legs 41e. These bottomlegs have inturned ends 41d inserted in the ends of an aperture 42a ofthe roller 42. This roller 42 rides on the tip end of the valve and thehanger 41 suspends the roller so that it will bear against the roundedend 1251" of the bottom strap 12.

As shown in Figure 13, for ease in assembly of any of the embodiments ofthis invention, the top strap 11 and the bottom strap 12 can haveapertures 43 and 44 respectively therethrough. The tube 13 has piercedoutturned projections 45 fitting the apertures 43 and 44. These piercedportions and holes facilitate proper alignment of the straps on the tubeand can be used as locators during assembly of the rocker arms of thisinvention.

Figure 14 indicates generally the manner in which the forces are appliedto the rocker arms of this invention. The rocker arm embodiment a ofFigures 4 and 5 has been selected as typical of the disclosures. Asshown in Figure 14, Pp is the force applied by or acting on the pushrod, Fv is the similar force of the valve stem and Fs is the resultingresisting force exerted by the rocker arm shaft on the bushing. It willbe noted that these forces are always in the same general directionsince their respective angles in relation to the rocker arm change onlya small amount due to the small rotation of the rocker arm. The rockerarms of the present invention thus have the top and bottom straps 11 and12 forming substantially true trusses.

As diagrammatically illustrated in Figure 15 the push rod end of therocker arm on which the force Fp is applied is translated to a force F'pin the top strap leg 11c and a force F"p in the bottom strap leg 120.These forces resist the push rod load Fp acting at the fulcrum of thestraps. In Figure 16 the corresponding vector diagram and forces for thevalve contact of the rocker are shown where the force Fv is translatedinto a force Fv' in the top strap leg 11b and a force F"v in the bottomstrap leg 12b. Thus, the forces acting on the right and left hand partsof the top strap where they join the bushing are not equal and opposite.There is a resultant force transmitted through the bushing and thebushing thus acts as a strut member or as the third member of atriangular truss.

In the rocker arms of this invention all of the metal in the strap isstressed uniformly and the rocker arms of this invention can, therefore,be made with light weight material to decrease the polar inertia of theassembly.

While a beam stressed to the same surface stress as a truss may be morerigid than a truss, it has been found feasible to increase the sectionof the straps 11 and 12 in the truss rocker arms of this invention togive the same or greater rigidity than that of a conventional beam unitand yet produce a lighter rocker arm with lower polar moment of inertia.

The following data illustrates the increased strength, and rigidity, andthe decreased weight and polar inertia of the truss type rocker arms ofthis invention as compared with standard beam type stamped rocker arms:

In Figure 17 there is illustrated the manner in which fiat matedtogether ends 46 and 47 of the straps 11 and 12 On the other hand, asshown in Figures 18 and 19, thespacer between the ends of the straps 11and 12 acts asa link 49 and as these ends are deflected upwardly asshown in Figure 19 the link 49 is swung inwardly at the bottom to arrestthe rotation and rigidify the assembly. The resultant force F mayactually be in an outward direction. The spacer and rivet assembly inthe short legs 11b and 12b of the straps, therefore, offsets the bend ofthe ends of the straps by pulling the strap in from the bottom as shownin Figure 19 resisting furtherbending. A link arrangement for the longlegs is not needed because the ends of these legs. are spaced aconsiderable distance from the rocker shaft support and bendingdeflection is negligible.

It will be noted in all of the rocker arms of this invention, the bottomstrap laps a considerable are of the bottom of the tube 13., This strap,therefore, reinforces the tube over the area that carries substantiallythe entire load Fs as shown by the force diagram in Figure 14.

From the above descriptions it will thus be understood that thisinvention now provides economical, light weight, low inertia truss typerocker arms including substantially flat top straps and bowed bottomstraps anchored to a bearing tube therebetween. The bearing tube ispositioned closer to the push rod actuated end of the rocker arm than tothe valve actuating end of the arm. The push rod actuated end has aspacer between the straps acting as a link to resist a beam bendingaction. The assemblies of straps, tubes, spacers, rivets and the like,can be secured in any conventional manner as by welding, riveting,brazing, or the like.

It will be understood that modifications and variations 7 may beeffected without departing from the scope of the novel concepts of thepresent invention.

1 claim as my invention:

1. A rocker arm comprising a metal tube, a bearing liner in said tube,top and bottom straps extending transversely of said tube, weld bondsuniting said straps with the tube, said top strap having a substantiallyflat contour and enveloping only a small portion of the tube, saidbottom strap lapping a substantial portion of the tube, said strapshaving short legs on one side of the tube and long legs on the otherside of the tube, a spacer between the ends of the short legs of thestraps, push rod means coacting with said ends, and the long legs of thestraps being substantially longer than the short legs and converging toprovide a valve contact end portion for therocker arm. v

2. A truss type rocker arm which comprises top and bottom truss members,an interposed bushing tube an- 1 chored thereto, said truss membersconverging at their ends to provide valve actuating and push rodactuated portions of the rocker arm, and said tube acting as a strutbetween the straps to coact therewith for forming a pair of triangulartrusses.

3. A rocker arm comprising top and bottom straps, a bushing between saidstraps and secured thereto, said straps projecting beyond the bushingsand converging to end portions, one end portion having relatively shortlegs and having opposed flat eyes, a spacer between said eyes, an eyeletextending through said eyes and said spacer, means securing said eyeletto said eyes, said long legs having mated together portions, and meansat the ends of the long legs adapted to engage the tip end of a valve.

4. A truss type rocker arm which comprises a pair of substantially flattop straps, the uppermost top strap having a corrugated rib portiontherein providing a passageway between the straps, a .U-shaped bottomstrap, a rock shaft bushing between the top and bottom straps andsecured thereto providing longitudinally spaced trusses, said, bushinghaving a lubricant aperture therethrough communicating with saidpassageway, said straps converging to flat eye end portions at one endthereof, a push rod receiving plug cooperable with another end of saidstraps, and a passageway connecting the push rod receiving portion ofsaid plug with said oil passage between the straps.

5. A rocker arm comprising a tubular bearing bushing, superimposed firstand second struts straddling the bushing and extending laterallythereof, a push rod engaging portion on one end of said struts, a valvetip engaging portion on the other end of said struts, and said strutsbeing connected only at the ends and through the bushing to providerigid triangular trusses with opposite side portions of the bushing.

6. A rocker arm which comprises a rock shaft bushing, a slightly bowedtop strap secured flatwise on said bushing and extending laterallythereof, a U-shaped bottom strap engaging the bottom portion of thebushing and secured flatwise thereon to underlie the top strap, saidstraps being spaced and converging on each side of the bushing to form avalve contact end and a push rod contact end, said top strap having ahollow open bottom hollow rib extending longitudinally from the bushingto the push rod contact end, said bushing having a hollow rib seating inthe rib of said top strap arranged to re ceive lubricant from a rockshaft in the bushing, and said bushing rib having an aperture fordirecting lubricant into the open bottom of the strap rib to flow alongthe strap rib to the push rod contact end.

. 7. A rocker arm which comprises a tubular rock shaft bushing, strapsstraddling said bushing and converging on opposite sides thereof toprovide trusses therewith, a rivet secured in one convergent end of thestraps having a valve tip contact head, a spacer between the otherconvergent ends of the straps, and a push rod engaging member carried bysaid other end.

References Cited in the file of this patent UNITED. STATES PATENTS547,136 Barr Oct. 1, 1895 1,164,405 Schaeffer Dec. 14, 1915 1,306,119Pharo June 10, 1919 1,467,964 Postol-Vinay Sept. 1, 1923 1,644,750 ShortOct. 11, 1927 1,699,657 Pagan Jan. 22, 1929 1,866,293 Chandler July 5,1932 1,964,770 Runge July 3, 1934 2,176,083 Leake Oct. 17, 19392,199,914 Haberstump May 7, 1940 2,272,166 Leake Feb. 3, 1942 2,469,564Leake May 10, 1949 2,572,968 Bachle Oct. 30, 1951 OTHER REFERENCESPublication: Smith, Welded Construction, Product Engineering, pp.388-389 July 1942.

